title: Clinical significance of low expression of Prostasin mRNA in human gastric cancer.
abstract: BACKGROUND
  Prostasin is considered to have suppressive activities against tumor progression. The aim of this study was to clarify its clinical significance in gastric cancer.
  
  
  METHODS
  Tumor and the corresponding normal samples were prepared from a total of 108 gastric cancer patients. Prostasin expression was assayed by real time reverse transcription (RT)-polymerase chain reaction (PCR) and by immunohistochemistry. Epigenetic silencing of the expression was examined by demethylation treatment. Survival was examined in Kaplan-Meier plots, and the relationship between its expression and clinicopathologic factors was statistically analyzed.
  
  
  RESULTS
  Prostasin mRNA expression was significantly down-regulated in tumor tissues. Immunohistochemistry confirmed loss of Prostasin expression in gastric cancer. Gastric cancer cell lines that did not express Prostasin mRNA retrieved its expression following demethylation treatment. In those patients whose tumor expressed Prostasin mRNA at reduced levels, we observed shorter survival (P = 0.0110), due to a higher incidence of lymph node metastasis (P = 0.0087), lymphatic permeation (P = 0.0542) and venous permeation (P = 0.0492).
  
  
  CONCLUSIONS
  Prostasin mRNA expression was frequently down-regulated in gastric cancer. Loss of expression might be regulated by epigenetic factors, contributing to the shorter survival. Reduced Prostasin mRNA expression might be a novel indicator for biological aggressiveness in gastric cancer.
authors.affiliation: Department of Surgery and Molecular Oncology, Medical Institute of Bioregulation, Kyushu University, 4546 Tsurumihara, Beppu 874-0838, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Sakashita
authors.forename: Koshi
authors.initials: K
authors.lastname: Mimori
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Tanaka
authors.forename: Kouichirou
authors.initials: K
authors.lastname: Tahara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Sawada
authors.forename: Masaichi
authors.initials: M
authors.lastname: Ohira
authors.forename: Kosei
authors.initials: K
authors.lastname: Hirakawa
authors.forename: Masaki
authors.initials: M
authors.lastname: Mori
mesh_terms: D000368:Aged; D019175:DNA Methylation; D015536:Down-Regulation; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008207:Lymphatic Metastasis; D008297:Male; D011379:Prognosis; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000378:metabolism* / Q000401:mortality*; D000099271:Prostasin
chemical_list: D012333:RNA, Messenger; D012697:Serine Endopeptidases; D000099271:Prostasin